Methods of controlling the migration of resin dispersions and resin binders in the manufacture of porous materials such as bonded nonwoven fabrics

ABSTRACT

Methods of controlling the migration of resin dispersions such as resin binders in the manufacture of porous materials such as bonded nonwoven fabrics comprising the use of a resin dispersion or resin binder composition comprising: (1) a metal ammine complex coordination compound; (2) a synthetic resin; and (3) a surfactant, at least one of the resin and surfactant components containing specific coordinating ligands capable of being affected by ions of said metals to control the total migration of the resin binder during its deposition.

United States Patent Drelich et al.

[ Oct. 30, 1973 METHODS OF CONTROLLING THE MIGRATION OF RESIN DISPERSIONS AND RESIN BINDERS IN THE MANUFACTURE OF POROUS MATERIALS SUCH AS BONDED NONWOVEN FABRICS Inventors: Arthur H. Drelich, Plainfield; Bobby R. Bowman, East Brunswick, both of NJ.

Johnson & Johnson, New Brunswick, NJ.

Filed: Apr. 5, 1972 Appl. No.: 241,110

Related US. Application Data Continuation-in-part of Ser. Nos. 66,003, Aug. 21, 1970, abandoned, and Ser. No. 194,908, Nov. 2, 1971.

Assignee:

U.S. Cl. ..ll7/63,1l7/138.8 E, l17/l38.8 F, 117/138.8 N, 1l7/l38.8 PV, 117/140 A, 117/161 UD, 117/161 UT Int. Cl B44d 1/44 Field of Search 117/38, 139.5 A, ll7/l38.8 A, 161 UD, 62.2, 63,140, 143 A,

145; 260/29.7 M, 29.6 MM, 29.2 N, 29.2 E

[56] References Cited UNITED STATES PATENTS 2,782,130 2/1957 Ness et al. 117/140 A 2,880,111 3/1959 Drelich et al. 117/140 R 3,009,822 ll/196l Drelich et al. 117/140 R Primary Examiner-William D. Martin Assistant Examiner-Theodore G. Davis Attorney-Alexander T. Kardos et al.

[57] ABSTRACT 10 Claims, 1 Drawing Figure fvrzmryw lavas/e METHODS OF CONTROLLING THE MIGRATION OF RESIN DISPERSIONS AND RESIN BINDERS IN THE MANUFACTURE OF POROUS MATERIALS SUCH AS BONDED NONWOVEN FABRICS This patent application is a continuation-in-part of copending patent applications Ser. No. 66,003, filed Aug. 21, 1970, and now abandoned and Ser. No. 194,908, filed Nov. 2, 1971. p

The present invention relates to synthetic resin binder compositions of use in the manufacture of porous, absorbent, fibrous sheet materials. More particularly, the present invention is concerned with the socalled bonded, nonwoven textile fabrics, i.e., fabrics produced from textile fibers without the use of conventional spinning, weaving, knitting or felting operations. Although not limited thereto, the invention is of primary importance in connection with nonwoven fabrics derived from oriented or carded fibrous webs composed of textile-length fibers, the major proportion of which are oriented predominantly in one direction.

Typical of such fabrics are the so-called MAS- SLINN nonwoven fabrics, some of which are described in greater particularity in U. S. Pat. Nos. 2,705,687 and 2,705,688, issued Apr. 5, 1955, to D. R. Petterson et al. and l. S. Ness et al., respectively.

Another aspect of the present invention is its application to nonwoven fabrics wherein the textile-length fibers were originally predominantly oriented in one direction but have been reorganized and rearranged in predetermined designs and patterns of fabric openings and fiber bundles. Typical of such latter fabrics are the so-called KEYBAK bundled nonwoven fabrics, some of which are described in particularity in U. S. Pat. Nos. 2,862,251 and 3,033,721, issued Dec. 2, 1958 and May 8, 1962, respectively, to F. Kalwaites.

Still another aspect of the present invention is its application to nonwoven fabrics wherein the textilelength fibers are disposed at random by air-laying techniques and are not predominantly oriented in any one direction. Typical nonwoven fabrics made by such procedures are termed isotropic nonwoven fabrics and are described, for example, in U. S. Pat. Nos. 2,676,363 and 2,676,364, issued Apr. 27, 1954, to C. H. Plummer et al.

And, still another aspect of the present invention is its application to nonwoven fabrics which comprise textile-length fibers and which are made basically by conventional or modified aqueous papermaking techniques such as are described in greater particularity in pending patent application Ser. No. 4,405, filed Jan. 20, 1970, and now abandoned by P. R. Glor and A. H. Drelich. Such fabrics are also basically isotropic" and generally have like properties in all directions.

The conventional base starting material for the majority of these nonwoven fabrics is usually a fibrous web comprising any of the common textile-length fibers, or mixtures thereof, the fibers varying in average length from approximately one-half inch to about two and one-half inches. Exemplary of such fibers are the natural fibers such as cotton and wool and the synthetic or man-made cellulosic fibers, notably rayon or regenerated cellulose.

Other textile length fibers of a synthetic or man-made origin may be used in various proportions to replace either partially or perhaps even entirely the previouslynamed fibers. Such other fibers include: polyamide fibers such as nylon 6, nylon 66, nylon 610, etc.; polyester fibers such as Dacron, Fortrel and Kodel, acrylic fibers such as Acrilan, Orlon and Creslan; modacrylic fibers such as Verel and Dynel; polyolefinic fibers derived from polyethylene and polypropylene; cellulose ester fibers such as Arnel and Acele;" polyvinyl alcohol fibers; etc.

These textile length fibers may be replaced either partially or entirely by fibers having an average length of less than about one-half inch and down to about onequarter inch. These fibers, or mixtures thereof, are customarily processed through any suitable textile machinery (e.g., a conventional cotton card, a Rando- Webber, a papermaking machine, or other fibrous web producing apparatus) to form a web or sheet of loosely associated fibers, weighing from about grains to about 2000 grains per square yard or even higher.

If desired, even shorter fibers, such as wood pulp fibers or cotton linters, may be used in varying proportions, even up to 100 percent, where such shorter length fibers can be handled and processed by available apparatus. Such shorter fibers have lengths less than A inch.

The resulting fibrous web or sheet, regardless of its method of production, is then subjected to at least one of several types of bonding operations to anchor the individual fibers together to form a self-sustaining web. One method is to impregnate the fibrous web over its entire surface area with various well-known bonding agents, such as natural or synthetic resins. Such over-all impregnation produces a nonwoven fabric of good longitudinal and cross strength, acceptable durability and washability, and satisfactory abrasion resistance. However, the non-woven fabric tends to be somewhat stiff and boardlike, possessing more of the properties and characteristics of paper or board than those of a woven or knitted textile fabric. Consequently, although such over-all impregnated nonwoven fabrics are satisfactory for many uses, they are still basically unsatisfactory as general purpose textile fabrics.

Another well-known bonding method is to print the fibrous webs with intermittent or continuous straight or wavy lines, or areas of binder extending generally transversely or diagonally across the web and additionally, if desired, along the fibrous web. The resulting nonwoven fabric, as exemplified by a product disclosed in the Goldman U.S. Pat. No. 2,039,312 and sold under the trademark MASSLINN," is far more satisfactory as a textile fabric than over-all impregnated webs in that the softness, drape and hand of the resulting nonwoven fabric more nearly approach those of a woven or knitted textile fabric.

The printing of the resin binder on these non-woven webs is usually in the form of relatively narrow lines, or elongated rectangular, triangular or square areas, or annular, circular, or elliptical binder areas which are spaced apart a predetermined distance which, at its maximum, is preferably slightly less than the average fiber length of the fibers constituting the web. This is based on the theory that the individual fibers of the fibrous web should be bound together in as few places as possible.

The nominal surface coverage of such binder lines or areas will vary widely depending upon the precise properties and characteristics of softness, drape, hand and strength which are desired in the final bonded product. In practice, the nominal surface coverage can be designed so that it falls within the range of from about percent to about 50 percent of the total surface of the final product. Within the more commercial aspects of the present invention, however, nominal surface cover ages of from about 12 percent to about 40 percent are preferable.

Such bonding increases the strength of the nonwoven fabric and retains substantially complete freedom of movement for the individual fibers whereby the desirable softness, drape and hand are obtained. This spacing of the binder lines and areas has been accepted by the industry and it has been deemed necessarily so, if the stiff and board-like appearance, drape and hand of the over-all impregnated nonwoven fabrics are to be avoided.

The nonwoven fabrics bonded with such line and area binder patterns have had the desired softness, drape and hand and have not been undesirably stiff or board-like. However, such nonwoven fabrics have also possessed some disadvantages.

For example, the relatively narrow binder lines and relatively small binder areas of the applicator (usually an engraved print roll) which are laid down on the fibrous web possess specified physical dimensions and inter-spatial relationships as they are initially laid down. Unfortunately, after the binder is laid down on the web fibrous web and before it hardens or becomes fixed in position, it tends to spread, diffuse or migrate whereby its physical dimensions are increased and its inter-spatial relationships decreased. And, at the same time, the binder concentration in the binder area is lowered and rendered less uniform by the migration of the binder into adjacent fibrous areas. One of the results of such migration is to make the surface coverage of the binder areas increase whereby the effect of the intermittent bonding approaches the effect of the overall bonding. As a result, some of the desired softness, drape and hand are lost and some of the undesired properties of harshness, stiffness and boardiness are increased.

Various methods have been proposed to prevent or to at least limit such spreading, diffusing or migration tendencies of such intermittent binder techniques.

For example, U. S. Pat. No. 3,009.822, issued Nov. 21, I961 to A. H. Drelich et al., discloses the use of a non-migratory regenerated cellulose viscose binder which is applied in intermittent fashion to fibrous webs under conditions wherein migration is low and the concentration of the binder in the binder area is as high as 35 percent by weight, basedon the weight of the fibers in these binder areas. Such viscose binder possesses inherently reduced spreading, diffusing and migrating tendencies, thereby increasing the desired softness, drape and hand of the resulting nonwoven fabric. This viscose binder has found acceptance in the industry but the use of other more versatile binders has always been the polyacrylic resins, the polyolefins, the synthetic rubbers, etc. Examples of condensation polymers are the polyurethanes, the polyamides, the polyesters, etc.

Of all the various techniques employed in carrying out polymerization reactions, emulsion polymerization is one of the most commonly used. Emulsion polymerized resins, notably polyvinyl chlorides, polyvinyl acetates, and polyacrylic resins, are widely used throughout many industries. Such resins are generally produced by emulsifying the monomers, stabilizing the monomer emulsion by the use of various surfactant systems, and then polymerizing the monomers in the emulsified state to form a stabilized resin polymer. The resin polymer is usually dispersed in an aqueous medium as discrete particles of colloidal dimensions (1 to 2 microns diameter or smaller) and is generally termed throughout the industry as a resin dispersion, or a resin emulsion or latex.

Generally, however, the average particle size in the resin dispersion is in the range of about 0.1 micron (or micrometer) diameter, with individual particles ranging up to l or 2 microns in diameter and occasionally up to as high as about 3 or 5 microns in size. The particle sizes of such colloidal resin dispersions vary a great deal, not only from one resin dispersion to another but even within one resin dispersion itself.

The amount of resin binder solids in the resin colloidal aqueous dispersion varies from about 1] 10 percent solids by weight up to about 60 percent by weight or even higher solids, generally dependent upon the nature of the monomers used, the nature of the resulting polymer resin, the surfactant system employed, and the conditions under which the polymerization was carried out.

These resin colloidal dispersions, or resin emulsions, or latexes, may be anionic, non-ionic, or even polyionic and stable dispersions are available at pHs of from about 2.5 to about 10.5.

The amount of resin which is applied to the porous or absorbent material varies within relatively wide limits, depending upon the resin itself, the nature and character of the porous or absorbent materials to which the resins are being applied, its intended use, etc. A general range of from about 4 percent by weight up to about percent by weight, based on the weight of the porous or absorbent material, is satisfactory under substantially all uses. Within the more commercial limits, however, a range of from about 10 to about 30 percent by weight, based on the weight of the porous or absorbent material, is preferred.

Such resins have found use in the coating industries for the coating of woven fabrics, paper and other materials. The resins are also used as adhesives for laminating materials or for bonding fibrous webs. These resins have also found wide use as additives in the manufacture of paper, the printing industry, the decorative printing of textiles, and in other industries.

in most instances, the resin is colloidally dispersed in water and, when applied from the aqueous medium to a porous or absorbent sheet material which contains additional water is carried by the water until the water is evaporated or otherwise driven off. If it is desired to place the resin only on the surface of the wet porous or absorbent sheet material and not to have the resin penetrate into the porous or absorbent sheet material, such is usually not possible inasmuch as diffusion takes place between the aqueous colloidal resin and the water in the porous material. In this way, the colloidal resin tends to spread into and throughout the porous material and does not remain merely on its surface.

Or, if it is desired to deposit the resin in a specific intermittent print pattern, such as is used in bonding nonwoven fabrics, the aqueous colloid tends to diffuse and to wick along the individual fibers and to carry the resin with it beyond the confines of the nominal intermittent print pattern. As a result, although initially placed on the nonwoven fabric in a specific intermittent print pattern, the ultimate pattern goes far beyond that due to the spreading or migration which takes place due to the diffusion of the water and the resin, until the water is evaporated or otherwise driven off.

We have discovered new resin binder compositions containing polymers colloidally dispersed in aqueous media and new methods of applying such resin binder compositions to porous or absorbent fibrous materials, whereby the resins are applied in a controlled, relatively non-migrating manner. If 'it is desired that the resin be placed only on the surface of the porous or absorbent material, our compositions and methods will allow this to be done. Furthermore, if it is desired that the resin be impregnated throughout the material, from one surface to the other surface, again, our composition and method will allow this to be done.

We have now discovered an improved method of controllably depositing colloidal resin compositions on porous or absorbent materials whereby spreading, diffusing, and migration of the resin are controlled and are markedly reduced and wherein the concentration of the resin in the resin binder area reaches exceptionally high values in short distances as measured at right angles to the bond edge. When applied to fibrous webs in the manufacture of non-woven fabrics, excellent strength is obtained in the resulting bonded fabrics along with textile-like softness, hand and drape.

The improved method involves the use of a resin dispersion which comprises from about 0.1 to about 60 percent by weight on a solids basis of a colloidal synthetic resin containing a coordinating ligand, said synthetic resin dispersion being stable at certain concentrations or degrees of dilution but which is unstable at lesser concentrations or greater degrees of dilution when in the presence of heavy metal ions such as chromium, nickel, cobalt, cadmium, zinc, vanadium, titanium, copper and aluminum.

The coordinating ligand is normally an acidic or proton donor group, especially those containing terminal hydroxy groups. Examples of hydroxy-containing coordinating ligands are: hydroxy Ol-l; carboxy --CO0l-l; sulfino SO(Ol-l); sulfo -SO,(OH); sulfonoamino Nl-ISO=(OH); aci-nitro=NO(Ol-l); hydroxyamino -Nl-l0l-l; hydroxyimino=NOl-l; etc. It is to be observed that these hydroxy-containing radicals contain a hydrogen atom which is capable of dissociating to form an H ion or proton.

The colloidal synthetic resins possessing a hydroxycontaining coordinating ligand are obtained by copolymerizing (1) from about 92 percent by weight to about 99 percent by weight of amonomer or a mixture of monomers of the group comprising vinyl halide, vinyl ester, or vinyl ether monomers including, for example, vinyl chloride, vinyl acetate and vinyl ethyl ether; olefin monomers such as ethylene and propylene; acrylic and methacrylic monomers including, for example, ethyl acrylate, ethyl hexyl acrylate, methyl acrylate, propyl acrylate, butyl acrylate, hydroxyethyl acrylate, dimethyl amino ethyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, N-isopropyl acrylamide, N-methylol acrylamide, methacrylamide; vinylidene monomers such as vinylidene chloride; diene monomers including, for example, 1 ,Z-butadiene, l,3-butadiene, 2-ethyl-1 ,3-butadiene; styrene monomers including, for example, styrene, 2- methyl styrene, 3-methyl styrene, 4-methyl styrene, 4- ethyl styrene, 4-butyl styrene; and other polymerizable monomers with (2) a relatively small amount, on the order of from about 1 percent by weight to about 8 percent by weight, of an unsaturated acid containing a terminal hydroxy group such as the 01,3 -unsaturated carboxylic acids including acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, crotonic acid, isocrotonic acid, angelic acid, tiglic acid, etc. Anhydrides of such acids, where they exist, are also of use. Other 01,13 -unsaturated acids are of use and include 2- sulfoethyl methacrylate, styrene sulfonic acid, vinyl phosphonic acid, etc.

It is to be appreciated that more than one monomer may be included in the polymerization with the 04,3 -'unsaturated acid. An outstanding example of the use of more than one monomer is the polymerization of butadiene and styrene with an 01,3 -unsaturated acid such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, or itaconic acid. Anhydrides, for example, maleic anhydride, are also of use.

To the resulting emulsion polymerized composition containing the colloidal resin with its coordinating ligand is added a small amount of from about 0.1 percent by weight to about 3 percent by weight, based on the weight of the synthetic resin solids, of a metal ammine complex coordination compound wherein the central metallic atom is chromium, nickel, cobalt, cadmium, zinc, or copper or aluminum.

Examples of such coordination compounds are:

hexammine chromium chloride a)e] a' 2 pentammine chloro chromium chloride [Cr(NH -Cl]Cl hexammine nickel chloride hexammine nickel bromide hexammine nickel chlorate a)a]( Oa)2 hexammine nickel iodide hexammine nickel nitrate tetrammine zinc carbonate tetrammine zinc sulfate diammine zinc chloride hexammine cobalt chloride l s)sl a hexammine cobalt iodide s)el 2 hexammine cobalt nitrate l a)s]( a)a hexammine cobalt sulfate l a)s] 4 hexammine cobalt bromide l a)e] '2 tetrammine zinc chloride l s)4l 2 tetrammine dinitro cobalt nitrate a)4( 2 )2 l ah;

diammine copper acetate a)2l( 2 a 2)2 tetrammine copper sulfate As defined herein, a metal ammine complex coordination compound is one of a number of types of metal complex compounds, usually made by addition of organic or inorganic atoms or groups such as ammonia (Ni-l to simple inorganic compounds containing the metal atom. Coordination compounds are therefore essentially compounds to which atoms or groups are added beyond the number possible of explanation on the basis of electrovalent linkages, or the usual covalent linkages, wherein each of the two atoms linked donate one electron to form the duplet. In the case of the coordination compounds, the coordinated atoms or groups are linked to the atoms of the coordination compound, usually by coordinate valences, in which both the electrons in the bond are furnished by the linked atoms of the coordinated group.

The emulsion polymerized ligand-containing synthetic resin and the coordination compound exist together ina stable emulsion form and normally do not agglomerate, coagulate or precipitate, as long as the stable concentration levels of Nl-hOl-l or degrees of dilution are maintained.

Subsequently, however, when the emulsion is diluted with water to a sufficiently low concentration of Nl-hOl-l, the resin immediately coagulates and agglomerates in place with no further spreading, diffusion or migration.

it is believed that, when the emulsion is diluted sufficiently, the metal cation is released from the metal ammine complex coordination compound and immediately attacks or reacts with the ligand-containing synthetic resin causing the resin particles to agglomerate or coagulate.

it is also to be appreciated that, when the emulsion is diluted sufficiently, the metal cation which is released from the metal ammine complex coordination compound also is capable of attacking or reacting with any other chemical compounds which are present and which possess anionic groups, particularly hydroxy, carboxy, sulfino, sulfo, and like acid'groups.

For example, the metal cation which is released immediately attacks a surfactant system which is anionic and contains surfactants such as alkyl aromatic sulfonic acids, alkyl sulfonic acids, the carboxylic acids, and other surfactants such as, for example, dodecyl benzene sulfonate, octyl benzene sulfonate, hexyl benzene sulfonate, octadecyl benzene sulfonate, cetyl sulfonate, hexyl sulfonate, dodecyl sulfonate, octadecyl sulfonate, and the sodium and potassium fatty acid soaps containing from five to 18 carbon atoms. Other anionic surfactants include sodium p-l-methyl alkyl benzene sulfonates in which the alkyl group contains from 10 to 16 carbon atoms, the sodium di-n-alkyl sulfosuccinates in which the alkyl groups contain from four to 12 carbon atoms, the potassium n-alkyl malonates in which the alkyl group contains from eight to 18 carbon atoms, the potassium alkyl tricarboxylates in which the alkyl group contains from six to 14 carbon atoms, the alkyl betaines in which the alkyl group contains from six to 14 carbon atoms, the ether alcohol sulfates, sodium nalkyl sulfates, containing from six to 18 carbon atoms, etc.

The amount of surfactant used may vary from about 0.1 to 5 percent by weight of the resin solids dependent on the type resin being polymerized and the conditions under which it is polymerized.

The specific surfactant which is selected for use in the resin composition does not relate to the essence of the invention. It is merely necessary that it possess the necessary properties and characteristics to carry out its indicated function of stabilizing the resin composition prior to the time that coagulation and precipitation of the resin is required. Additionally, in the event that it is desired that the surfactant assist in or promote the coagulation and precipitation function, then it must possess the necessary anionic groups, as described hereinbefore, which are capable of reaction due to the presence of the metal cations released from the metal ammine complex coordination compound.

The mechanism of instant agglomeration, coagulation and precipitation of the colloidal resin binder may therefore be triggered subsequent to dilution by reaction of the metal cation with either the colloidal resin, or the anionic surfactant, or both.

The dilution may be effected in different ways in order to activate the reaction mechanism. For example, the porous or absorbent fibrous material may be pretreated by being pre-wet with a sufficient quantity of an aqueous medium, preferably water, whereby the colloidal resin composition immediately becomes sufficiently diluted. Or, if desired, the colloidal resin composition may be first printed on the porous or absorbent fibrous material and then substantially immediately treated with the aqueous medium such as water to effect the dilution whereupon the colloidal resin particles substantially immediately agglomerate or coagulate in place with no further spreading, diffusion or migration.

It is believed that the coagulation and precipitation take place by dilution alone wherein the NFL, groups in the metal ammine complex coordination compound break down and become Nl-hOl-l in the excess water being carried by the fibrous web. By this reaction, the metal cations are released, coagulating and precipitating the resin. The reaction is believed to be as follows:

Me(NH Y+XI-I O 2 Me(cation)+xNH Ol-l+Y- (anion) wherein Me is a metal such as disclosed herein, x is a whole number from 2 to 8 (and more commonly 2,4 or 6), and Y is an anion such as chloride, iodide, bromide, sulfite, sulfate, nitrite, nitrate, carbonate, acetate, borate, phosphate, citrate, chlorate, oxalate, etc.

It is to be appreciated that Me and Y normally form compounds, the formation of which can be explained on the basis of electrovalent linkages, or the usual covalent linkages, wherein each of the two atoms linked donate one electron to form the duplet.

It is believed that the addition of the water to the resin dispersion causes the equilibrium of the reaction mechanism to shift to the right whereby the metallic cations are released to bring about the described coagulation and precipitation of the resin. Lesser amounts of water cause the equilibrium of the reaction mechanism to move to the left favoring the continued stability of the metal ammine complex coordination compound and the resin dispersion.

The amount of the water applied to the fibrous web varies widely, depending upon many factors, the most important of which is the nature, concentration, properties and characteristics of the synthetic resin, the metal ammine complex coordination compound, and the surfactant system in which they are stabilized. Nor mally, the amount of water applied to the fibrous web is in the range of from about 140 to about 280 percent, and preferably from about 160 to about 220 percent, based on the weight of the fibrous web being treated. Such amounts are controlled by the use of suitable conventional vacuum apparatus, nip-rolls, squeeze-rolls, etc.

The amount of water which is applied to the fibrous web prior to the printing of the resin binder also affects the degree of control exercised over the coagulation and migration. The greater the amount of water, the greater is the control and the more rapid is the coagulation and the less is the migration. On the other hand, the less the amount of water in the fibrous web, the less is the control exercised, the less rapid is the coagulation, and the greater is the migration.

It is also to be realized that the greater the amount of water of dilution, then the greater is the degree of penetration of the resin binder into the fibrous web. And, the lesser the amount of water of dilution, then the lesser is the degree of penetration of the resin binder into the fibrous web.

The degree of coagulation may be lowered even more and the degree of migration may be increased by the inclusion in the pre-wetting water of a small amount of an alkaline or basic material such as ammonium hydroxide. The pH remains alkaline, just as it does in other variations of this invention, and the coagulation and precipitation are purely the result of the dilution.

When printed on a pre-wetted fibrous web during the manufacture of nonwoven fabrics, the total migration of the resin binder solids may be reduced to as little as about 50 percent or less beyond the originally deposited area. In some instances, the migration is relatively negligible. Normally, however, the increase in area of the resin binder solids, even under the most adverse conditions, does not materially exceed about 200 percent. Such values are to be compared to increases in binder migration of at least about 300 percent and up to about 800 percent when emulsion polymerized resins are applied to fibrous porous absorbent sheet materials, unaided by the principles dlsclosed herein.

The concentration of the binder resin solids in the binder area is correspondingly increased when utilizing the principles of the present invention and is in the range of from about 50 percent by weight to about 120 by weight, and more normally from about 60 to about percent by weight, based on the weight of the fibers in the binder area.

The excellent migration control exercised over the resin binder is illustrated in the drawing in which:

The FIGURE is a graph or histogram of binder deposition On a nonwoven fabric showing surface coverage and concentration of binder when carried out in accordance with the principles of the present invention, as compared to the results obtained when not carried out in accordance with the principles of the present invention. with The FIGURE establishes the sharpness and distinctness of the edges or boundary lines which exist between the bonded areas and the unbonded areas. This is attested to by the fact that the optical density of the bonded nonwoven fabric sharply increases from about 0.0 Optical Density to as much as from about 0.6 to about 1.0 Optical Density in merely moving a distance of about 1 mm. (0.04 inch) or less, lengthwise of the nonwoven fabric from the unbonded area into the bonded area. This feature will be described in greater detail hereinafter.

As defined herein, Optical Density varies generally proportionately to the concentration of binder and is equal to the logarithm (base 10) of the ratio of (l) the intensity of an incident ray (1,) falling upon a transparent or a translucent medium to (2) the intensity of a transmitted ray (I,) which passes through the transparent or translucent medium. ThiS quantity (log l lh) is therefore a measure of the degree of ability of light to pass through the medium. When the fibers are made transparent and the binder is made opaque, the Optical Density is a measure of the intensity or the concentration of the binder on the nonwoven fabric. Since it is frequently not possible to make the fibers transparent, an alternate procedure, based on differential staining of fiber and binder, measuring light reflectance may be used.

Inasmuch as the Optical Density is a logarithmic function and difficult to compare directly, Optical Transparency will also be used in this description of the invention. As defined herein, Optical Transparency is equal to I,/l,, or it is the direct ratio of the intensity of the transmitted light (1,) to the intensity of the incident light (1,). Such a term is more easily employed for direct comparison purposes.

It is extremely important to describe the procedures which are used for determining (1) the sharpness and the distinctness of the boundary lines which exist between the bonded areas and the unbonded areas; (2) the border or edge feathering and total surface coverage of the binder; (3) the optical densities and transparencies of various points in the bonded areas; (4) the concentration of the binder in the bonded areas; etc.

It has long been known that the actual width of a bond on a nonwoven fabric is greater than the nominal width of the engraved line on the print roll which applies the binder to the fibrous web during the making of a bonded nonwoven fabric. The difference between the two widths is, of course, the binder migration.

It is relatively easy to measure the nominal width of the engraved line on the print roll. However, a problem has always existed as to the best method for accurately measuring the actual bond width on the bonded nonwoven fabric. Incorporating a dye or pigment in a resin binder and measuring the resultant colored binder area is misleading. It is now known that the binder spreads much farther in the fibrous web than the pigment or dye because of a chromatographic phenomenon among the fibers. As a result, a subjective viewing of a resin bonded non-woven fabric will merely reveal the width of the pigmented or dyed area which is considerably less than that of the bonded area covered by the binder.

Incorporating a pigment or dye in a viscose binder as compared to a resin binder, and measuring the resulting colored binder area is also misleading, although it is believed that in the case of bonding with viscose, as differentiated from bonding with a resin binder, the binder stays more closely with the pigment or dye. In any event, however, the pigmented or dyed areas are less than the bonded fabric areas which are covered with a viscose binder.

In the case of practically all the resins used for binder purposes, differential staining techniques may be employed so that the rayon fibers are unstained and remain relatively white while the resin binder becomes stained and takes on an intense color. Even under magnification, the colored resin binder is discernible and distinguishable from the rayon fibers. Such differentially stained non-woven fabrics have often been studied under relatively low power microscopes and the width of the actual binder line has been subjectively estimated by comparison to a standard scale, usually in the microscope eyepiece. The binder edge, especially in the case of a migrated print line, gradually fades to zero or substantially zero, and the visual estimation of the binder width is therefore a difficult, subjective procedure. It is now known that prior efforts to estimate binder widths have led to low estimates inasmuch as the extremes of the binder-feathering have been neglected.

The improvements brought about by the present invention are determined by measuring actual bond widths and relative binder content across a bond stripe by an objective method using an analytical instrument for the actual measurements. These improved methods will be described in greater detail hereinafter.

It has been observed that it is characteristic of migrated print bonded patterns to show a binder feathering near the bond edges. On the other hand, when migration is controlled, binder feathering is nonexistent and the line of demarcation between bonded area and non-bonded area is sharp. The feathering, however, in a migrated binder reflects the diffusion of binder into the water of the wet web and also the capillary absorption of liquid binder by the web structure. In contrast, when binder has been coagulated to control migration, diffusion, capillarity and feathering near the edge of the bond are essentially nonexistent.

An unusual feature of the feathering phenomenon is the fact that it is more pronounced on one side of the bonded area. It is believed that this is caused by the fact that the binder, as it is applied by an engraved print roll, tends to smear and migrate more on the trailing side of the applied binder. The leading edge, that is, the edge first contacted by the print roll, is usually cleaner with less smearing and less migration.

When binder migration is controlled, the total amount of binder applied may be selected to be the same but the binder is controllably restricted to a smaller area within the web. Hence, binder concentration within the bond area is higher and the line of demarcation between bond and free-fiber areas is much sharper in controlled nonwoven fabrics. In fact, it is believed that the feathered edge of the bond area deleteriously affects nonwoven properties for the following reasons:

1. The low binder content in the feathered areas is sufficient to cause stiffness, but is not sufflcient to impart good strength.

2. The highest concentration of binder attainable in the bond area in non-controlled print areas is not sufficient to make bonds as strong as the fibers. On the other hand, when binder migration is controlled, the binder content is high enough to equal fiber strengths, but not so high that the bond feels nubby. Furthermore, the high concentration of binder in the bonded areas in a controlled printed fabric approaches (but does not reach) a continuous binder film. Therefore, a better carry-through of binder properties in the web is obtained, especially strength and resilience.

Several new concepts, and unexpected results are believed to be embodied in the controlled migration fabrics which have been made. A laboratory method for giving numerical values to the fiber-bond transition area has been developed, based on the staining properties of binder and the optical characteristics of a stained bond area. By this method, the nonwoven fabric is stained with the proper dye or chemical reagent and the reflected light from the surface of the various areas of the fabric is measured. The intensity of staining across a bond is measured by means of its magnified image on the ground glass of a camera. The microscope image of the surface of the stained fabric on the camera ground glass is scanned with a light sensing instrument and a graph of the intensity of reflected light (as Optical Density) versus location across a bond is made.

In order for this procedure to be quantitative and reproducible, it is necessary to specify many of the details as follows. The print-bonded nonwoven fabric is differentially stained in a 1 percent solution of Celliton Fast Violet 6BA (manufactured by General Aniline and Film), by immersion for one minute in boiling solution and rinsing in cool water until the cellulosic fibers become white. This dye will stain all of the common types of binders including acrylics, vinyl acetates, butadienestyrene rubbers, vinyl chloride polymers, etc. Other dyes may be used as long as the base fibers are essentially undyed, and the resin itself is dyed an intense color. The fabrics are air-dried and mounted on a flat white Surface. The mounted sample is placed on a graduated mechanical stage under a ground glass camera using lenses and distances to enlarge the image 20.0X by methods well known in the photographic and microscopic art. This specimen is illuminated by two small spot lights mounted at about 45 above the specimen and at from each other, that is, opposite each other in a straight line.

The probe of an optical densitometer is fixed at the focusing plane (the ground glass) of the camera. It is convenient to use a reflex housing so that the specimen can be examined visually or the reflected image can be measured simply by turning a mirror to deflect the light for observation or for measurement respectively. The

size of the probe is set at a 4X4 millimeter square.

The two lights illuminating the specimen are carefully placed to minimize the formation of shadows. An

area of the test specimen which is completely free of 5 binder is moved underneath the sensing area, and by means of the controls in the densitometer, the needle reading is set at 0 Optical Density.

The stage micrometer is manipulated to move the specimen in definite intervals of 0.1 mm. only along the axis perpendicular to the bond line. As the magnified image is traversed stepwise across the probe, light reflectivity readings are taken. Light reflectivity is measured as Optical Density. As mentioned above, the actual size of the light sensing probe is 4X4 millimeters and is fixed to the screen where a 20.0X magnified image is projected. At an actual movement of 0.1 millimeter, the apparent movement is magnified to 2.0 millimeters at 20X magnification, hence, the probe of 4X4 mm. dimension reads an overlapping area with each consecutive reading. The purpose of choosing this probe size and obtaining overlap is to tend towards smoothing the curve. Otherwise, an erratic reading is obtained.

In other words, the differentially stained test sample, under constant illumination, is traversed across the field while a fixed light sensing probe measures the light reflectance of its magnified image, hence, the comparative binder content across a single bond unit. The intensity of the reflected light, in units of Optical Density yields a comparative measure of binder content across a bond pattern unit.

This procedure can be used on any nonwoven fabric so long as the rayon fibers or other fibers are white and are not colored significantly by the dye which stains the binder.

Such procedures establish that:

l. The binder content within the binder area is higher in controlled migration samples, and is in the range of about 50-120 percent binder content (based on fiber weight in the same area).

2. The binder penetrates essentially throughout the entire thickness of the web. This is in sharp contrast to the products of dry printing where the binder stays'on one side of the web.

3. The binder content across the binder area is more uniform in the controlled sample, that is, there is a virtual absence of feathering and practically no transition area between clean fiber and bond area.

Inasmuch as it can be arranged that the total amount of binder material in each bond unit of a controlled and an uncontrolled migrational sample of a nonwoven fabric is the same, as determined by chemical analysis, the areas under the curves in the histograms of these samples will denote the same amount of binder. However, as an artifact of the test procedures; based on the saturation color of the binder stain, the raw data taken by the hereindescribed procedures usually shows an apparently appreciable higher area under the curve for the migrated samples.

Hence, it is therefore necessary that the raw data be normalized by multiplying it by a factor less than one to bring the area under its curve to that of the controlled migration binder area. In this way, the controlled and uncontrolled migration bond areas can be examined and compared. This normalization has been 14 done for the FIGURE, but further refinement thereof may be necessary.

It is to be appreciated that regardless of whether raw data or normalized data is used, the zero points and the distances required to go from zero binder content to maximum binder content or to go from zero to maxi mum Optical Density are unchanged. On the other hand, however, the slopes of the curves and the apparent peak Optical Densities are changed.

The invention will be further illustrated in greater detail by the following specific examples. It should be understood, however, that although these examples may describe in particular detail some of the more specific features of the invention, they are given primarily for purposes of illustration and the invention in its broader aspects is not to be construed as limited thereto.

EXAMPLE I A fibrous card web weighing about 570 grains per square yard and comprising percent rayon fibers 1% denier and 1% inches in length is intermittently print-bonded by the rotogravure process using an engraved roll having 6 horizontal wavy lines per inch. The width of each line as measured on the engraved roll is 0.024 inch.

The composition by weight of the resin binder form ulation used for the intermittent print-bonding is:

l. 10 lbs. ofa 50 percent solids latex of GAF 243 terpolymer of butadiene (46%), styrene (51%), and afi-unsaturated carboxylic acid (2%).

2. 4 lbs. of distilled water.

3. 1 lb. of a 10 percent solution of a thickening agent,

Acrysol 51, a copolymer of acrylic acid.

4. 15 grams Pluronic L101 polyol ethylene oxide condensates of hydrophobic bases of propylene oxide and propylene glycol nonionic surfactant.

5. 90 grams of a 48 percent solution of zinc tetrammine sulfate metal coordination complex containing 17 percent zinc oxide equivalent or 0.1 lb. zinc tetrammine sulfate (actual).

The fibrous card web is pretreated or pre-moistened with a large amount of water to the extent of about 250 percent moisture based on the weight of the fibers in the web.

The extra dilution with water is sufficient by itself to upset the stability of the resin dispersion when applied to the web and it instantly coagulates and precipitates on the very wet fibrous web. The printed web is then processed, dried and cured as described previously.

The width of the binder line in the finished product is about 0.056 inch which represents a controlled total migration of about percent. The surface coverage of the binder is about 33.6 percent. The percent binder in the bonded nonwoven fabric is about 17.4 percent. The concentration of binder in the binder area is about 52 percent, based on the weight of the fibers therein. The maximum Optical Density is about 0.79 corresponding to a minimumOptical Transparency which is about 0.17.

The graph or histogram in FIG. 1 shows the binder concentration and surface coverage. The slope of the curves in this Figure are 84 and 86 respectively and it requires only 0.7 mm. and 0.5 mm. (0.028 inch and 0.020 inch) at the leading and trailing edges, respectively, to change from substantially zero binder concentration to substantially maximum binder concentration in the binder area.

The resulting nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent crossresilience.

EXAMPLE II The procedures of Example I are followed substantially as set forth therein except that the carboxylated butadiene styrene polymer is replaced by polyvinyl acetate. No zinc tetrammine sulfate or other ammine complex is used. All other conditions remain the same. Print-bonding is conventional and follows standard plant manufacturing processing. Coagulation and precipitation of the binder is not very rapid. Processing, drying and curing are conventional. The width of the binder stripe in the final product is about 0.189 inch which represents a very large total migration of about 690 percent. The surface coverage of the binder is high and is about 75.6 percent due to the excessive binder feathering. The total binder content in the bonded nonwoven fabric is about 17.4 percent. The concentration of binder in the binder area is only about 23 percent, based on the weight of the fibers therein due to the relatively high degree of binder feathering. The product is stiff and is not soft and does not possess a desirable drape or hand.

The histogram developed from an analysis of the resulting product is shown as a dash curve in the FIG- URE. It is to be observed that the peak Optical Density is only about 0.40 whereas the peak Optical Density for the invention binder in the Figure is 0.79. The slopes of the curves are about 38 and 48 and rise from substantially zero binder concentration to substantially maximum binder concentration in relatively long distances of 2.4 mm. (0.096 inch) and 2 mm. (0.080 inch).

EXAMPLE III The procedures of Example I are followed substantially as set forth therein except that the coordination complex compound is zinc tetrammine carbonate rather than zinc tetrammine sulfate. The results are generally comparable and the bonded nonwoven fabric is generally comparable in properties and characteristics to the bonded nonwoven fabric obtained in Example I.

EXAMPLE IV The procedures of Example I are followed substantially as set forth therein except that the zinc tetrammine sulfate is replaced by an equivalent amount of cobalt hexammine chloride.

The results are generally comparable and the bonded nonwoven fabrics obtained are generally comparable to those obtained in Example I.

EXAMPLE V The procedures of Example I are carried out substantially as set forth therein except that the zinc tetrammine sulfate is replaced by an equivalent amount of copper diammine acetate.

The results are generally comparable and the bonded nonwoven fabrics obtained are generally comparable to those obtained in Example I.

EXAMPLE VI The procedures of Example I are followed substantially as set forth therein with the exception that the percentage of the 0:,B -unsaturated carboxylic acid is decreased to 1 percent and the percentages of the butadiene and styrene are proportionately increased.

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and migrationis held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE VII EXAMPLE VIII The procedures of Example I are followed substantially as set forth therein with the exception that the percentage of the 04,)3 -unsaturated carboxylic acid is increased to 6 percent and the percentages of the butadiene and styrene are proportionately decreased.

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and migration is held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE IX The procedures of Example I are followed substantially as set forth therein with the exception that the binder formulation comprises 46 percent butadiene, 51 percent styrene, and 2 percent itaconic acid, plus a sodium salt of a phosphate ester as an anionic surfactant. Coagulation and precipitation take place satisfactorily. Total migration is controlled and held to a minimum. The resulting bonded nonwoven fabric is very comparable to the bonded nonwoven fabric obtained in Example I.

EXAMPLE X The procedures of Example I are followed substantially as set forth therein with the exception that the quantity of the coordination complex is decreased from grams zinc tetrarnmine sulfate (0.1 lb.) to 45 grams (0.05 lb.).

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately .upon being printed on the wet fibrous web and migration is held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric has excellentstrength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE XI The procedures of Example I are followed substantially as set forth therein with the exception that the quantity of the coordination complex is increased from 90 grams solution (0.1 lb. solids) to 135 grams solution (0.15 lb. solids).

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and migration is held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE XII EXAMPLE XIII The procedures of Example I are followed substantially as set forth therein with the exception that the terpolymer used therein is replaced by National Starch P306-3, a copolymer of 97 percent acrylic monomer and 3 percent acrylic acid.

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and migration is heldto a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE XIV The procedures of Example I are followed substantially as set forth therein with the exceptionthat the terpolymer used therein is replaced by a terpolymer of ethylene, vinyl acetate, andan 01,13 -unsaturated carboxylic acid.

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and migration is held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE XV The procedures of Example I are carried out substantially as set forth therein except that the GAF 243 carboxylated butadiene-styrene terpolymer is replaced by an equivalent amount of a terpolymer of 51% butadiene, 46% styrene, and 2% acrylic acid.

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and the total migration is held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric is generally comparable to the bonded non-woven fabric obtained in Example 1.

EXAMPLE XVI The procedures of Example I are carried out substantially as set forth therein except that the GAP 243 carboxylated butadiene-styrene terpolymer is replaced by an equivalent amount of a terpolymer of 51% butadiene, 46% styrene, and 2% methacrylic acid.

The carboxylated terpolymer resin binder dispersion coagulates and precipitates substantially immediately upon being printed on the wet fibrous web and the total migration is held to a minimum. Conventional processing, drying, and curing are employed. The resulting bonded nonwoven fabric is generally comparable to the bonded nonwoven fabric 'obtainedin Example I.

EXAMPLES XVII XVIII & XIX

The procedures of Example I are followed substantially as set forth therein except that the pretreatment with water is changed so that the fibrous web takes up (a) (b) and (c) 220% moisture, based on the weight of the fibers in the web.

Coagulation and precipitation of the binder take place as disclosed in Example I and the results are generally comparable to those obtained in Example I.

EXAMPLE XX The procedures of Example I are followed substantially as set forth therein with the exception that the rayon fibers are replaced by bleached cotton fibers.

The results are comparable and the resulting nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience.

EXAMPLE XXI The procedures of Example I are followed substantially as set forth therein with the exception that the web is pretreated with a very dilute ammonium hydroxide solution (0.025 percent Nl-LOl-I) rather than with water. The resulting pH is between 8 and 9.

The results are comparable and the resulting nonwoven fabric has excellent strength, excellent softness, drape and hand, and excellent cross-resilience. The migration, however, is slightly inferior to the migration when water alone is used.

EXAMPLE XXII The procedures of Example I are followed substantially as set forth therein with the exception that waterinsoluble polyvinyl alcohol fibers (Kurashiki 2.5 denier) are used instead of the rayon fibers.

The properties and characteristics of the resulting nonwoven fabric are set forth in the following Table wherein there arealso set forth the propertiesand characteristics of the productof Example I'for comparison purposes.

Example l Example XXII Long Cross Long Cross Tensile strength-dry 31.83 2.87 38.7 7.0 Thwing Albert 3-ply 1 (pounds) Tensile strength-wet 15.03 2.23 28.13 5.33 Thwing Albert 3-ply (pounds) Tensile strength 0.89 L97 lnstron l-ply Elongation 65% 65% Grain weight per 676 532 square yard Bulk per one ply 0.013" 0.013 Absorbency time 7 sec. 4 sec. Absorbent capacity 5 to 39 grams 5 to 37.8 grams Launderability Good Excellent The improvement in strength, both wet and dry, is outstanding.

EXAMPLE XXIII The procedures of Example I are followed substantially as set forth therein with the exception that tetrammine zinc chloride is used to replace the zinc tetrammine sulfate. The results are generally comparable to results obtained in Example I except that the: process using the chloride which is a more inexpensive material is preferred for economic reasons. The resulting bonded nonwoven fabric has excellent strength, excellent softness, desirable drape and hand, and excellent cross-resilience.

Having now described the invention in specific detail and exemplified the manner in which it may be carried into practice, it will be readily apparent to those skilled in the art that innumerable variations, applications, modifications, and extensions of the basic principles involved may be made without departing from its spirit and scope.

What is claimed is:

l. A method of applying a synthetic resin binder to a fibrous web of overlapping, intersecting fibers and controlling its migration thereon which comprises: applying to a fibrous web of overlapping, intersecting fibers a stable, colloidal aqueous dispersion comprising: (i) a synthetic resin; (2) a surfactant, at least one of said resin and surfactant components having a hydroxycontaining coordinating ligand; and (3) a metal ammine complex coordination compound, said dispersion being applied to said fibrous web in a predetermined, intermittent print pattern of spaced areas; and substantially immediately diluting said dispersion whereby a metal cation is released from said metal ammine complex coordination compound to substantially immediately destroy the stability of said dispersion and coagulate said resin in said spaced areas with a minimum of migration therefrom.

2. A method as defined in claim 1 wherein the metal ammine complex coordination compound has the formula Me(NH ),Y

wherein Me is a metal selected from the group consisting of chromium, nickel, cobalt, cadmium, zinc, vanadium, titanium, copper, and aluminum; 1: is a whole number from 2 to 8, inclusive; and Y is an anion.

3. A method as defined in claim 1 wherein the metal ammine complex coordination compound is zinc tetrammine sulfate.

4. A method as defined in claim 1 wherein the metal ammine complex coordination compound is zinc tetrammine carbonate.

5. A method as defined in claim 1 wherein the metal ammine complex coordination compound is cobalt hexammine chloride.

6. A method as defined in claim 1 wherein the metal ammine complex coordination compound is copper diammine acetate.

7. A method as defined in claim 1 wherein said aqueous dispersion comprises: from about 0.1 to about percent by weight of said synthetic resin; from about 0.01 to about 5 percent by weight, based on the weight of said'resin, of said surfactant; and from about 0.1 to about 3 percent by weight, based on the weight of said resin, of said metal ammine complex coordination compound.

8. A method as defined in claim 1 wherein the dispersion is diluted with water.

9. A method as defined in claim 1 wherein the dispersion is diluted with ammonium hydroxide.

10. A method of applying a stable, colloidal, aqueous, resin dispersion to porous materials and controlling its migration thereon which comprises: applying to porous materials a stable, colloidal, aqueous, resin dispersion comprising: (1) a synthetic resin; (2) a surfactant; at least one of said resin and surfactant components having a hydroxy-containing coordinating ligand; and (3) a metal ammine complex coordination compound; and substantially immediately diluting said stable, colloidal, aqueous, resin dispersion whereby a metal cation is released from said metal amine complex coordination compound to substantially immediately destroy the stability of said dispersion and coagulate said resin whereby the migration of said resin on said porous materials is controlled. 

2. A method as defined in claim 1 wherein the metal ammine complex coordination compound has the formula Me(NH3)xY wherein Me is a metal selected from the group consisting of chromium, nickel, cobalt, cadmium, zinc, vanadium, titanium, copper, and aluminum; x is a whole number from 2 to 8, inclusive; and Y is an anion.
 3. A method as defined in claim 1 wherein the metal ammine complex coordination compound is zinc tetrammine sulfate.
 4. A method as defined in claim 1 wherein the metal ammine complex coordination compound is zinc tetrammine carbonate.
 5. A method as defined in claim 1 wherein the metal ammine complex coordination compound is cobalt hexammine chloride.
 6. A method as defined in claim 1 wherein the metal ammine complex coordination compound is copper diammine acetate.
 7. A method as defined in claim 1 wherein said aqueous dispersion comprises: from about 0.1 to about 60 percent by weight of said synthetic resin; from about 0.01 to about 5 percent by weight, based on the weight of said resin, of said surfactant; and from about 0.1 to about 3 percent by weight, based on the weight of said resin, of said metal ammine complex coordination compound.
 8. A method as defined in claim 1 wherein the dispersion is diluted with water.
 9. A method as defined in claim 1 wherein the dispersion is diluted with ammonium hydroxide.
 10. A method of applying a stable, colloidal, aqueous, resin dispersion to porous materials and controlling its migration thereon which comprises: applying to porous materials a stable, colloidal, aqueous, resin dispersion comprising: (1) a synthetic resin; (2) a surfactant; at least one of said resin and surfactant components having a hydroxy-containing coordinating ligand; and (3) a metal ammine complex coordination compound; and substantially immediately diluting said stable, colloidal, aqueous, resin dispersion whereby a metal cation is released from said metal amine complex coordination compound to substantially immediately destroy the stability of said dispersion and coagulate said resin whereby the migration of said resin on said porous materials is controlled. 